Have you been diagnosed with SIBO? Or maybe you haven’t been diagnosed, but you’ve heard this buzzword, and think you’re experiencing some of the symptoms. So, what exactly is SIBO? Small Intestinal Bacterial Overgrowth (SIBO) is, basically, too much bacteria in the wrong place. Both your small and large intestines house bacteria, but most of it should be in your large intestine (aka colon). The overpopulation of bacteria in your small intestines is what we call SIBO.
This article will give a brief overview of the symptoms, possible causes, diagnosis, and treatment options for SIBO. We’ll focus mainly on the various diet therapy options that are out there, specifically the reduction of fermentable carbohydrates for symptom relief.
You may only experience some of these symptoms but you don’t need to experience all to have SIBO:
- Bloating, abdominal pain, belching, gas, diarrhea, constipation, weight loss
- Sometimes difficulty concentrating or “brain fog”
- Nutrient deficiencies: Vitamin B12, Vitamin D, iron
Possible causes (or risk factors)
- Irritable bowel syndrome (IBS)
- Inflammatory bowel disease (IBD)
- Celiac disease
- motility disorders
- history of some types of gastric surgery
The 2020 ACG Clinical Guidelines for SIBO discussed the use of antibiotics as a treatment option. The most widely used is a 14-day course of the non-absorbable antibiotic, rifaximin. Other antibiotic therapies were discussed, but rifaximin was the most widely used. None of the studies mentioned retesting patients for SIBO following antibiotic therapy. Of note, antibiotics were only recommended in those SIBO positive patients that were symptomatic.
Other therapies that may be used in treatment are herbal products and prokinetic agents. You should discuss the best mode of treatment for you with your gastroenterologist and healthcare team.
At this time, no studies are looking specifically at diet therapy for SIBO treatment. The ACG guidelines do discuss limiting fermentable carbohydrates (possibly the Low FODMAP diet), but nowhere in the literature are any diets shown to be the “SIBO diet”.
With that, some of the diets are recommended by medical professionals to help relieve digestive symptoms of SIBO, but none of them will actually cure SIBO. Below are five common diets that may be used during SIBO treatment to aid with symptoms.
- Cedars Sinai Low Fermentation Diet: This diet was created by Dr. Mark Pimentel and his team at Cedars Sinai. It focuses on limiting fermentable carbohydrates, fiber, lactose, and fructose. The diet allows easy-to-digest sugars and starches and focuses on the benefits of meal spacing for your migrating motor complex (MMC). The MMC is a cleaning wave that occurs in your small intestine every 90-120 minutes. You need to be in a fasting state for this to occur. This means meal spacing 3-4 hours and no snacking in between meals. While this diet was created by one of the top IBS & SIBO researchers, it hasn’t been studied for IBS or SIBO. It does, however, pull on research from diets like the Low FODMAP diet. Some key differences from Low FODMAP are that white bread is allowed (it’s easy to digest) as are all nuts, but beans and lentils are off-limits (even in small amounts).
- Bi-phasic Diet: This is a combination of the Specific Carbohydrate Diet (SCD) and the Low FODMAP diet. The SCD diet is research-based in those with Inflammatory Bowel Disease, but there is no evidence for IBS or SIBO at this time. While both SCD and Low FODMAP are evidence-based, they haven’t been studied in those with SIBO.
- GAPS diet (Gut and Psychology Syndrome): This diet is extremely restrictive, long, and complicated. It has six phases and can last up to 2 years. There are no research studies proving its efficacy for SIBO or other health conditions.
- Elemental Diet: This is the most restrictive diet as it relies on an easy-to-digest formula. There is no solid food allowed on this type of diet. There is a small study that showed it was beneficial in normalizing lactulose on a breath test. This type of diet should only be done under the care of a healthcare provider.
- Low FODMAP Diet: The Low FODMAP diet was created and studied at Monash University. It is a three-phase approach that focuses on limiting fermentable carbohydrates that cause digestive symptoms. There are a couple of key differences between this diet and the Low Fermentation diet. First, this diet has a time frame to follow. There is an elimination period followed by reintroduction. Second, Low FODMAP emphasizes various portion sizes. This allows for a more diverse diet.
Tips for Diet and Symptom Relief
- Focus on meeting your nutrient needs first. SIBO can create nutritional deficiencies due to a decrease in food intake and/or malabsorption. The goal is to be able to eat the most nutritionally complete diet while limiting symptoms. If you’re not sure where to start or if you’re meeting your nutritional needs, make an appointment with a Registered Dietitian.
- Consider Meal spacing. One aspect of the Cedars Sinai Low Fermentation diet is the use of meal spacing. This means that you limit snacking to allow your MMC a chance to “clean house”. While this can be a beneficial aspect for some, it’s not ideal if you have other digestive issues (like gastroparesis) that require small, frequent meals. When in doubt, just eat!
- Consider reducing fermentable carbohydrates. Anecdotally, a diet low in fermentable carbohydrates (like the Low FODMAP diet) can be successful in limiting digestive symptoms of SIBO. A good first step would be to review the Low FODMAP diet recommendations and see how many high FODMAP foods you’re actually eating. You may be able to reduce the portion size or swap out for a Low FODMAP alternative. Talk with your dietitian about the best way to approach reducing fermentable carbohydrates for you. There is not always a one size fits all approach!
- Over-restriction can create food fears. Food fears may develop in those with digestive disorders because some foods can make you sick or create pain. While elimination diets may be beneficial for some, in others they can only exacerbate food fears. Kate Scarlata wrote a great post about GI Disorders & Food Fears where you can find out more about it.
- Take it easy on supplements. While some supplements are important to treat nutritional deficiencies, take it easy on the slew of products that are promoted to help treat SIBO and its symptoms. Some supplements may contain gastric irritants or fermentable carbohydrates (like chicory root) that may actually make you feel worse. Other supplements, like the lactase enzyme or peppermint oil capsules, may decrease some of your digestive symptoms. You can read more about supplements and belly soothers here, but be sure to talk to your healthcare team before starting any new supplements.
It’s important to note, this is not medical advice. It is not recommended to implement a Low FODMAP (or any of the other diet therapies mentioned) without discussing it with your healthcare team. As noted above, some symptoms of SIBO include weight loss and nutrient deficiencies. Starting a restrictive diet on your own may worsen some of these symptoms, so if you think that you may have SIBO, speak with your healthcare provider to make sure any changes are the right fit for you!
Pimentel, Mark MD, FRCP(C), FACG1; Saad, Richard J. MD, FACG2; Long, Millie D. MD, MPH, FACG (GRADE Methodologist)3; Rao, Satish S. C. MD, PhD, FRCP, FACG4 ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth, The American Journal of Gastroenterology: February 2020 - Volume 115 - Issue 2 - p 165-178 doi: 10.14309/ajg.0000000000000501.
Pimentel, M., Constantino, T., Kong, Y., Bajwa, M., Rezaei, A., & Park, S. (2004). A 14-day elemental diet is highly effective in normalizing the lactulose breath test. Digestive diseases and sciences, 49(1), 73–77. https://doi.org/10.1023/b:ddas.0000011605.43979.e1.
Scarlata, Kate, et al. “Gi Disorders + Food Fears.” For A Digestive Peace of Mind-Kate Scarlata RDN, 15 Oct. 2019, blog.katescarlata.com/2019/10/14/gi-disorders-food-fears/.